Aquifer replenishment system

ABSTRACT

A concrete structure for replenishing an aquifer and a method for constructing the same is provided. The structure is comprised of a pavement layer with surface drains that extend through the pavement layer and into an aggregate leach field. The leach field includes leach lines spanning the leach field. An aggregate drain extends from the leach field into a sand lens. Precipitation which falls upon the structure thus flows through the surface drain, absorbed into the aggregate leach field, and transported to the aggregate drains by way of aggregate leach lines. The water is then absorbed into the sand lens, ultimately replenishing the aquifer. Existing conventional pavement structures are retrofitted by the removal of a section of the pavement, and filling the same with porous concrete.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. Application Ser. No.12/011,682 entitled AQUIFER REPLENISHMENT SYSTEM filed Jan. 29, 2008 nowabandoned. Ser. No. 12/011,682 is a divisional of Ser. No. 11/489,006filed Jul. 19 2006; now U.S. Pat. No. 7,351,004.

STATEMENT RE: FEDERALLY SPONSORED RESEARCH/DEVELOPMENT

Not Applicable

BACKGROUND

1. Technical Field

The present invention generally relates to concrete structures and themethods for forming the same. More particularly, the present inventionrelates to concrete structures and forming methods that enhance thereplenishment of underground water in aquifers.

2. Description of Related Art

As is generally understood, a common source of fresh water forirrigation, human consumption, and other uses is groundwater. Usablegroundwater is contained in aquifers, which are subterranean layers ofpermeable material such as sand and gravel that channel the flow of thegroundwater. Other forms of groundwater include soil moisture, frozensoil, immobile water in low permeability bedrock, and deep geothermalwater. Among the methods utilized to extract groundwater includedrilling wells down to the water table, as well as removing it fromsprings where an aquifer intersects with the curvature of the surface ofthe earth.

While groundwater extraction methods are well known, much considerationhas not been given to the replenishment thereof. It is not surprisingthat many aquifers are being overexploited, significantly depleting thesupply. The most typical method of aquifer replenishment is throughnatural means, where precipitation on the land surface is absorbed intothe soil and filtered through the earth before reaching the aquifer.However, in arid and semi-arid regions, the supply cannot be renewed asrapidly as it is being withdrawn because the natural process takesyears, even centuries, to complete. It is well understood that in itsequilibrium state, groundwater in aquifers support some of the weight ofthe overlying sediments. When aquifers are depressurized or depleted,the overall capacity is decreased, and subsidence may occur. In fact,such subsidence that occurs because of depleted aquifers is partiallythe reason why some cities, such as New Orleans in the state ofLouisiana in the United States, are below sea level. It is wellrecognized that such low-lying and subsided areas have many attendantpublic safety and welfare problems, particularly when flooding or otherlike natural disasters occur.

The problem of rapid depletion is particularly compounded in developedareas such as cities and towns, where roads, buildings, and otherman-made structures block the natural absorption of precipitationthrough permeable soil. Generally, building and paving materials such asconcrete and asphalt are not porous, in that water cannot move throughthe material and be absorbed into the soil. In fact, porous materialwould be unsuitable for construction of buildings, where internalmoisture is desirably kept to a minimum. Thus, these developed areas aretypically engineered with storm drainage systems whereby precipitationis channeled to a central location, marginally cleaned of debris,bacteria, and other elements harmful to the environment which werepicked up along the drainage path, and carried out to the sea. Insteadof allowing precipitation to absorb into the ground, modern developedareas transport almost all surface water elsewhere.

One of the methods for replenishing aquifers is described in U.S. Pat.No. 6,811,353 to Madison, which teaches a valve assembly for attachmentto aquifer replenishment pipes. However, the use of such replenishmentsystems required frequent human intervention. Furthermore, in order forthe water in the aquifer to remain clean, existing clean water had to bepumped in. Additionally, the volume of water that was able to be carriedto these re-charging locations was limited, thus limiting thereplenishment capacity.

Changes to paving materials have also been considered. As is well knownin the art, concrete is a composite material made from aggregate and acement binder, the most common form of concrete being Portland cementconcrete. The mixture is fluid in form before curing, and after pouring,the cement begins to hydrate and gluing the other components together,resulting in a relatively impermeable stone-like material. Byeliminating the aggregate of gravel and sand, the concrete formedminiature holes upon curing, resulting in porous concrete. This form ofconcrete, while allowing limited amounts of water to pass through, wasunsuitable for paving purposes because of its reduced strength.Additionally, the aforementioned drainage systems were still requiredbecause the porous concrete was unable to handle all of the water in atypical rainfall. Structures designed to increase the strength whilemaintaining porosity have been attempted, whereby reinforcement in theform of rods, rebar, and/or fibers were incorporated into the structure.Nevertheless, the strength of the structure was insufficient because ofthe reduced internal bonding force of the concrete due to the lack of anaggregate.

Therefore, there is a need in the art for an aquifer replenishmentsystem for collecting precipitation and absorbing the same into thepavement and the soil in the immediate vicinity. There is also a needfor aquifer replenishment system that are capable of withstandingenvironmental stresses such as changes in temperature, as well asstructural stresses such as those associated with vehicle travel.Furthermore, there is a need for an aquifer replenishment system thatcan be retrofitted into existing pavement structures.

BRIEF SUMMARY

In light of the foregoing problems and limitations, the presentinvention was conceived. In accordance with one embodiment of thepresent invention, an aquifer replenishing pavement is provided, whichlies above soil having a sand lens above an aquifer, and a clay layerabove the sand lens. The structure is comprised of: an aggregate leachfield abutting the subgrade (typically comprised of clay); and a layerof suitable surface paving material such as reinforced concrete orasphalt, abutting the aggregate leach field. Additionally, one or moresurface drains extend through the concrete layer, and one or moreaggregate drains extend from the aggregate leach field to the sand lens.The surface drains have a higher porosity than the paving layer, and isfilled with rocks. According to another aspect of the invention, leachlines having a higher porosity than the surrounding leach field areprovided. The surface drains are in direct fluid communication with theleach lines, and the leach lines are in direct fluid communication withthe aggregate drains.

An aquifer replenishing concrete paving method is also provided,comprising the steps of: (a) clearing and removing a top soil layeruntil reaching a clay layer; (b) forming one or more aggregate drainsthrough the clay layer to a sand lens; (c) forming an aggregate leachfield above the clay layer; (d) forming a pavement layer above theaggregate leach field; and (e) forming surface drains extending theentire height of the pavement layer. Additionally, forming of theaggregate leach field also includes the step of forming one or moreleach lines therein.

In accordance with another embodiment of the present invention, anaquifer replenishing concrete gutter for use on a road surface with anelevated curb section is provided. The gutter is comprised of a porousconcrete section having an exposed top surface in a co-planarrelationship with the road surface, supported by the elevated curbsection and the side surface of the road. According to another aspect ofthe present invention, a cut-off wall is provided to further support theporous concrete section. A bore extending from the porous concrete downto the aquifer is also provided, and is filled with rocks.

An aquifer replenishing concrete gutter formation method is provided,comprising the steps of: (a) forming a gutter section between anelevated curb section and a road surface; (b) boring a hole in thegutter section into the aquifer; (c) filling the hole with rocks; (d)filling the gutter section with porous concrete; and (e) curing theporous concrete. In accordance with another aspect of the presentinvention, step (a) includes removing a section of the road surfaceadjacent to the elevated curb section. Finally, step (a) also includesforming a cut off wall extending downwards from the road surface andoffset from the elevated curb section.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features and advantages of the various embodimentsdisclosed herein will be better understood with respect to the followingdescription and drawings, in which like numbers refer to like partsthroughout, and in which:

FIG. 1 is a cross-sectional view of the surface of the earth;

FIG. 2 is a perspective cross-sectional view of a road surface aquiferreplenishment system in accordance with an aspect of the presentinvention;

FIG. 3 is a cross-sectional view of a gutter aquifer replenishmentsystem in accordance with an aspect of the present invention;

FIG. 4 is a cross-sectional view of a conventional road;

FIG. 5 is a cross-sectional view of a conventional road excavated forretrofitting an aquifer replenishment system in accordance with anaspect of the present invention;

FIG. 6 is a cross-sectional view of conventional road after excavationand formation of a cut-off wall in accordance with an aspect of thepresent invention; and

FIG. 7 is a cross sectional view of a road after excavating a borereaching an aquifer and filling the same with rocks, and depicts thepouring of concrete into the gutter section in accordance with an aspectof the present invention.

DETAILED DESCRIPTION

The detailed description set forth below in connection with the appendeddrawings is intended as a description of the presently preferredembodiment of the invention, and is not intended to represent the onlyform in which the present invention may be constructed or utilized. Itis to be understood, however, that the same or equivalent functions maybe accomplished by different embodiments that are also intended to beencompassed within the spirit and scope of the invention.

With reference now to FIG. 1, a cross sectional view of the earth'ssurface is shown. Atmosphere 30 is shown with clouds 32 releasingprecipitation 34, falling towards the ground 50. As is well understood,ground 50 is comprised of top soil layer 52. Underneath top soil layer52 is clay layer 54, and underneath that is sand lens 56. Aquifer 60 isa layer of water, and can exist in permeable rock, permeable mixtures ofgravel, and/or sand, or fractured rock 58. Precipitation 34 falls on topsoil layer 52, and is gradually filtered of impurities by the varyinglayers of sand, soil, rocks, gravel, and clay as it moves through thesame by gravitational force, eventually reaching aquifer 60. In thecontext of the above natural features, the present invention will bedescribed.

Referring now to FIG. 2, a first embodiment of the present inventiveconcrete paving system 100 is shown. Situated above clay layer 54 is anaggregate leach field 82 comprised of sand and gravel particles. Aboveaggregate leach field 82 is a pavement layer 80, which by way of exampleonly and not of limitation, is concrete composed of Portland cement andan aggregate. Pavement layer 80 may be reinforced with any reinforcementstructures known in the art such as rebar, rods and so forth forincreased strength. Preferably, the reinforcement structure has the samecoefficient of thermal expansion as the pavement material, for example,steel, where concrete is utilized, to prevent internal stresses inincreased temperature environments. By way of example only and not oflimitation, pavement layer 80 has reinforcement bars 90. It will beappreciated by one of ordinary skill in the art that the pavement layer80 need not be limited to architectural concrete, and asphalt and otherpavement materials may be readily substituted without departing from thescope of the present invention.

Extending from the top surface to the bottom surface of pavement layer80 are one or more surface drains 84. Due to the fact that non-porousconcrete, that is, concrete having aggregate mixed into the cement,permits little water to seep through, surface drains 84 expedite thewater flow into aggregate leach field 82. Typically, by way of exampleonly and not of limitation, surface drains 84 are filled with rocks toprevent large debris such as leaves and trash from clogging the same.

Within aggregate leach field 82 are one or more leach lines 86, whichassist the transfer of fluids arriving through surface drains 84. By wayof example only, leach lines 86 are in direct fluid communication withsurface drains 84. Leach lines 86 have a higher porosity than thesurrounding leach field 82 to enable faster transmission of fluids.Leach field 82 is also capable of absorbing water, and in fact, certainamounts are absorbed from leach lines 86. Additional water flowing fromsurface drains 84 is also absorbed into leach field 82. In this fashion,water is distributed across the entire surface area of leach field 82,resulting in greater replenishment of the aquifer. A person of ordinaryskill in the art will recognize that the leach field 82 acts as a filterby gradually removing particulates from precipitation, and resulting incleaner water in the aquifer.

As is well understood in the art, clay has a lower porosity as comparedto an aggregate of, for example, sand, gravel, or soil. In order toexpedite the transmission of water into the aquifer, aggregate drains 88extend from aggregate leach field 82, through clay layer 54, and intosand lens 56. Therefore, a minimal amount of water is absorbed into theclay layer 54, and the replenishment process is expedited.

After the water flows from leach field 82 into sand lens 56 viaaggregate drains 88, it is dispersed throughout sand lens 56, tricklingthrough to the aquifers in the vicinity. The water in the aquifer isthus replenished through largely natural means, namely the filtrationprocess involved in absorbing precipitation through aggregate leachfield 82 and sand lens 56, despite the existence of a non-porousmaterial such as concrete overlying the ground surface in the form ofpavement layer 80.

The aquifer replenishment system as described above is generally formedover previously undeveloped land, or any land that has been excavated toa clay layer 54. Thus, surfaces that have been previously paved by othermeans must first be removed so that the natural water absorptionmechanisms of the earth are exposed. After this has been completed,aggregate drains 88 are drilled from the exposed clay surface 54 intosand lens 56. After filling the aggregate drains 88 with aggregate, agenerally planar aggregate leach field 82 is formed. Contemporaneously,leach lines 86 are formed, and is encapsulated by the aggregate whichconstitutes leach field 82. After leach field 82 is constructed,concrete reinforcements 90 are placed, and uncured concrete is poured tocreate pavement layer 80.

With respect to the formation of surface drains 84, any conventionallyknown methods of creating generally cylindrical openings in concrete maybe employed. For example, before pouring the uncured concrete, hollowcylinders may be placed and inserted slightly into leach field 82 toprevent the concrete from flowing into the opening. Yet another exampleis pouring the concrete and forming a continuous layer, and drilling theconcrete after curing to form surface drain 84. It is to be understoodthat any method of forming surface drain 84 is contemplated as withinthe scope of the present invention.

With reference to FIG. 3, a second embodiment of the aquiferreplenishing system 200 is shown, including an elevated curb section192, a gutter section 196, and a road pavement section 190. Roadpavement section 190 is comprised of a pavement layer or pavementsurface 195, which by way of example only and not of limitation, isarchitectural concrete, asphalt concrete, or any other paving materialknown in the art, and is supported by base course 194. Base course 194is generally comprised of larger grade aggregate, which is spread andcompacted to provide a stable base. The aggregate used is typically ¾inches in size, but can vary between ¾ inches and dust-size.

In accordance with the present invention, gutter section 196 has aporous concrete gutter 184 in which the top surface thereof is in asubstantially co-planar relationship with the top surface of pavementsurface 195. Optionally, porous concrete gutter 184 is supported by base185 which is composed of similar aggregate material as base course 194.Furthermore, extending from optional base 185 into aquifer 60 is a rockfilled bore 188. As a person of ordinary skill in the art willrecognize, a bore filled with rocks will improve the channeling of waterdue to its increased porosity as compared with ordinary soil. Optionalbase 185 and porous concrete gutter 184 is laterally reinforced by cutoff walls 183 and elevated curb section 192. The cut off walls 183 aredisposed on opposing sides of the porous concrete gutter 184 and thebase 185 between the elevated curve section 192 and the pavement surface195. It is expressly contemplated that the cut off walls 183 may bepre-cast or cast in place.

When precipitation falls upon road pavement section 190, the water ischanneled toward gutter section 196. Porous concrete gutter 184 permitsthe precipitation to trickle down to aquifer 60. When optional base 185and rock filled bore 188 is in place, there is an additional filtereffect supplementing that of the porous concrete gutter 184. A similarresult can be materialized where the water drains from the upper surfaceof elevated curb section 192, or precipitation directly falls uponporous concrete gutter 184. Please note a large surface drain may beused in lieu of the porous concrete gutter.

This embodiment is particularly beneficial where retrofitting the gutteris a more desirable solution rather than re-paving the entire roadsurface. In a conventional road pavement as shown in FIG. 4, pavementsurface 195 and base course 194 extend to abut elevated curb section192. In preparation for retrofitting gutter section 196, a section ofpavement surface 195 and base course 194 is excavated as shown in FIG.5, leaving a hole 197 defined by the exposed surfaces of elevated curbsection 192, base course 194, and pavement surface 195. This is followedby the optional step of pouring and curing a cut-off wall 183 asillustrated in FIG. 6, which, as discussed above, serves to reinforcethe gutter section 196. One or more bores 188 are drilled down toaquifer 60, and filled with rocks, as shown in FIG. 7. An optional baseof aggregate 185 is formed above rock filled bore 188, and compacted byany one of well recognized techniques in the art. Finally, a volume ofporous concrete mixture, that is, a concrete without sand or otheraggregate material, is poured and cured, forming porous concrete gutter184. While recognizing the disadvantages of using porous concrete,namely, the reduced strength of the resultant structure, a person ofordinary skill in the art will also recognize that gutter section 196sustains less stress thereupon in normal use as compared to roadpavement section 190.

The above description is given by way of example, and not limitation.Given the above disclosure, one skilled in the art could devisevariations that are within the scope and spirit of the inventiondisclosed herein. Further, the various features of the embodimentsdisclosed herein can be used alone, or in varying combinations with eachother and are not intended to be limited to the specific combinationdescribed herein. Thus, the scope of the claims is not to be limited bythe illustrated embodiments.

1. An aquifer replenishing gutter for filtering liquid toward anaquifer, the gutter configured for use with an elevated curb and apavement layer having an exposed surface, the gutter comprising: aporous concrete section disposable between the pavement layer and theelevated curb, the porous concrete section having: an exposed topsurface and an opposing bottom surface, the exposed top surface being inco-planar relationship with said exposed surface of the pavement layer;an aggregate base including a rock filled bore, the aggregate base beingdisposable between the bottom surface of the porous concrete layer andthe aquifer to allow liquid to drain from the pavement layer to theaquifer via the porous concrete section and the aggregate base; and apair of cut off walls disposed on opposing lateral sides of the porousconcrete section and extending from the porous concrete section towardthe aquifer to laterally support to the porous concrete section.
 2. Theaquifer replenishing gutter set forth in claim 1, wherein the aggregatebase includes a top surface abutting said bottom surface of said porousconcrete section.
 3. The aquifer replenishing gutter of claim 1 whereinthe porous concrete section includes a first side surface disposable inabutting relation with said elevated curb, and a second side surfacedisposable in abutting relation with said pavement layer.
 4. An aquiferreplenishing gutter for filtering liquid toward an aquifer, the gutterconfigured for use with a pavement layer having an exposed surface, thegutter comprising: an elevated curb; a porous concrete sectiondisposable between the pavement layer and the elevated curb; and anaggregate base including a rock filled bore, the aggregate base beingdisposable between the porous concrete layer and the aquifer to allowliquid to drain from the pavement layer to the aquifer via the porousconcrete layer and the aggregate base.
 5. The aquifer replenishinggutter of claim 4, wherein the aggregate base defines a top surfaceabutting said bottom surface of said porous concrete section.
 6. Theaquifer replenishing gutter of claim 4, further comprising a pair of cutoff walls disposed on opposing lateral sides of the porous concretesection and extending from the porous concrete section toward theaquifer to laterally support the porous concrete section.
 7. The aquiferreplenishing gutter of claim 4 wherein the porous concrete section isabutting the elevated curb.
 8. The aquifer replenishing gutter of claim4 wherein the porous concrete section includes a first side surfaceabutting said elevated curb, and a second side surface disposable inabutting relation with said pavement layer.
 9. An aquifer replenishinggutter for filtering liquid toward an aquifer, the gutter comprising: apavement layer defining an exposed surface; an elevated curb disposed inspaced relation to the pavement layer; a porous concrete sectiondisposed between the pavement layer and the elevated curb; and anaggregate base including a rock filled bore, the aggregate base beingdisposable between the porous concrete section and the aquifer to allowliquid to drain from the pavement layer to the aquifer via the porousconcrete section and the aggregate base.
 10. The aquifer replenishinggutter of claim 9, wherein the aggregate base defines a top surfaceabutting said bottom surface of said porous concrete section.
 11. Theaquifer replenishing gutter of claim 9, further comprising a pair of cutoff walls disposed on opposing lateral sides of the porous concretesection and extending from the porous concrete section toward theaquifer to laterally support to the porous concrete section.
 12. Theaquifer replenishing gutter of claim 9, wherein the porous concretesection defines an exposed surface in co-planar relationship to theexposed surface of the pavement layer.
 13. The aquifer replenishinggutter of claim 9 wherein the porous concrete section is abutting thepavement layer.
 14. The aquifer replenishing gutter 9 wherein the porousconcrete section is abutting the elevated curb.
 15. The aquiferreplenishing gutter of claim 14 wherein the porous concrete section isabutting the pavement layer.